1. Field of the Invention
This invention relates to a resin composition which can be cured by irradiation of an active energy ray, such as UV-rays, electron beams, etc., particularly to an active energy ray curing type resin composition which is excellent in adhesion to substrates, such as glass, ceramics, plastic films, etc., in chemical resistance and in mechanical strength, also has high sensitivity and high resolution as a pattern forming material, and is suitable for formation of a pattern comprising a cured film of high precision. The active energy ray curing type resin composition is a resin composition which can be formed into a solid photosensitive sheet (dry film).
2. Related Background Art
In recent years, active energy ray curing type resins have been frequently used as coating materials, inks, sealing materials, resist materials and pattern forming materials. Active energy ray curing type resins as pattern forming materials were used for preparation of printing plates at the initial stage, but they have been recently utilized also for construction materials for precise instruments such as ink jet recording heads as disclosed in Japanese Patent Application laid-open No. 43876/1982, in addition to having been utilized in of electronic industries for print wirings, integrated circuits, etc.
Active energy ray curing type resins used in various fields as mentioned above are generally used as coating solutions or dry films. In the use thereof as solutions, advantages due to maintaining the resin film in solid state, particularly after coating and before irradiation with an active energy ray, include 1) easy formation of a thick film, 2) possible shortening of working time due to absence of fluidity and 3) easy pattern formation. On the other hand, advantages when using the resin as a dry film may include 1) formation of a pattern having a uniform and precise film thickness, 2 ) simple work with easy pattern formation, 3 ) little amount of volatiles with concomitant reduction of odor leading to no detriment to the work environment, etc.
However, active energy ray curing type resins which have hitherto been used for pattern formation, particularly dry film types, mainly utilize the curability of acrylic esters and are inferior in adhesion to a substrate. Also, such an acrylic dry film gives a pattern, by curing by irradiation with an active energy ray, which has a large tendency to absorb water absorption and is susceptible to marked deterioration in adhesiveness, mechanical strength, electrical insulation, etc., which may be considered to be caused by hydrolysis of the ester groups, particularly when contacted with an alkaline solution. For this reason, this type of resin has of poor durability when high mechanical strength or chemical resistance is demanded in protective coatings or construction materials such as for precise instruments, etc.
On the other hand, in recent years, without recourse to curability of acrylic esters as mentioned above, curing systems of epoxy resins utilizing active energy ray have been developed as disclosed in, for example, Japanese Patent Publications Nos. 14277/1977, 14278/1977 and 14294/1977. Epoxy resins in themselves have no curability with an active energy ray, but the curing systems of the epoxy resins demonstrated in the above patent publications cure the epoxy resins in the presence of a small amount of a catalyst which releases a Lewis acid by irradiation of an active energy ray, whereby a cured film having excellent water resistance, chemical resistance, mechanical strength or adhesiveness with a substrate is stated to be obtained. However, the active energy ray curing type resin utilizing the above curing system of epoxy resin can be used only in a solution, and it is difficult for it to be maintained after coating as a solid coating on a substrate, whereby it has been difficult to obtain a high precision, high resolution pattern as suited for a construction material in a precise instrument such as an ink jet recording head as mentioned above. Also, almost nothing is considered about utilization as a dry film, and this type of resin also had no satisfactory performance as a material for pattern formation of high precision and high resolution.
As described above, in the prior art, there has been no material which is capable of forming a precise pattern with excellent adhesion on various substrates, and which pattern has also high durability as a construction material.